Trunking between two switches

[joepc]

I have two Catalst 2960 switches and I have two VLANs. Default VLAN 1 and VLAN 22. My second VLAN 22 works fine on the core switch. I have a couple of ports that are trunked and can access it fine. Now I need to be able to communicate on VLAN 22 between the two switches but can not. Communication between VLAN 1 works fine.

I enabled trunking on the uplink ports between the two switches and that doesn't work. I am just using switchport mode trunk No encapsulation or anything. Any ideas???


Thanks!!!

 

[unclerico]

post a config of the uplink ports on all devices involved

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[ISPKing]

and post sho spann and sho int status

CCNP

 

[joepc]

******Switch port uplink from core switch to 2nd switch:
!
interface FastEthernet0/3
description uplink to Cisco NW1
switchport mode trunk
!


******Switch port uplink to core switch:

!
interface FastEthernet0/3
switchport mode trunk
!

 

[unclerico]

what are you using as your core switch?? post the output from sh int f0/3 trunk

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[joepc]

Fixed it. I needed to configure a port on the 2nd switch with VLAN 22 which actually "created" VLAN 22. Then I removed VLAN 22 from the port. This now lets the trunk ports pass VLAN 22 traffic.

I was just under the assumtion that by default any/all VLAN tags would get passed through a trunk port.

 

[unclerico]

yes, by default a trunk port will pass traffic for all vlans, but the vlans need to exist on all switches in the path.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[imbadatthis]

read up on VTP....



We must go always forward, not backward
always up, not down and always twirling twirling towards infinity.

 

[Quadratic]

Don't read up on VTP.

In my opinion, it is a slight convenience for a major problem waiting to happen. Also VTP pruning ironically creates broadcast traffic that you can avoid with manual pruning. To quote Cisco Press: "The benefits of dynamic propagation of vlan information across the network are not worth the potential for unexpected behavior due to operational error".
(Designing Cisco Network Service Architectures, 2nd edition, page 41)

CCNP, CCDP

 

[VinceWhirlwind]

I agree. I've used VTP and I quite liked it, but I've also seen the results of people not using it properly, which are disastrous.

But frankly, why would you really want something like VLANs propagated dynamically? Your VLANs should exist exactly where your network design says they should exist and nowhere else.

 

[vipergg]

I think it has a place in a design where you have many vlans across multiple switches and you are moving them around a lot . If you don't understand the potential gotchas of using vtp and how to avoid the dangers then you probably shouldn't be working on networks anyway .

 

[Quadratic]

A design where 'you have many vlans spanning through many switches and you need to move them around a lot' is usually a poor design to begin with. Having said that, I think it's unreasonable to say VTP is good because you know what you're doing, since networks generally grow and you can't speak for the VTP understanding of everyone in a tiered support staff. You're playing with fire to rely on no one ever making that kind of mistake anywhere in that L2 domain.

CCNP, CCDP

 

[VinceWhirlwind]

I agree with Quadratic - Murphy's Law is *not* about blaming people for their incompetence when something goes wrong, it's about designing systems without obvious pitfalls.